Egg Catches Sperm - Sperm Doesn't Penetrate Egg

Well, forget everything you know about fertilization and conception. Eggs actually catch sperm vs. sperm penetrating the egg. This amuzing article explains more:

The Aggressive Egg
When it comes to describing fertilization, biologists have got it all wrong. The egg is no passive lady-in-waiting.
by David H. Freedman (www.discovermagazine.com)

From the article

They had started the year before with a simple experiment--measuring human sperm’s ability to escape and swim away from a tiny suction pipet placed against the side of the sperm cell’s head. To the team’s great surprise, the sperm turned out to be feeble swimmers; their heads thrashed from side to side ten times more vigorously than their bodies pushed forward. It makes sense, says Martin. The last thing you’d want a sperm to be is a highly effective burrower, because it would end up burrowing into the first obstacle it encountered. You want a sperm that’s good at getting away from things.

The team went on to determine that the sperm tries to pull its getaway act even on the egg itself, but is held down against its struggles by molecules on the surface of the egg that hook together with counterparts on the sperm’s surface, fastening the sperm until the egg can absorb it. Yet even after having revealed the sperm to be an escape artist and the egg to be a chemically active sperm catcher, even after discussing the egg’s role in tethering the sperm, the research team continued for another three years to describe the sperm’s role as actively penetrating the egg.